Electrochemical cells are devices that convert fuel and oxidant to electrical energy. Electrochemical cells generally include an anode electrode and a cathode electrode separated by an electrolyte. A variety of known electrochemical cells fall within a category of cells often referred to as solid polymer electrolyte (SPE) cells. An SPE cell typically employs a membrane of an ion exchange polymer that serves as a physical separator between the anode and cathode while also serving as an electrolyte. SPE cells can be operated as electrolytic cells for the production of electrochemical products or they may be operated as fuel cells for the production of electrical energy. The most well known fuel cells are those which operate with gaseous fuels such as hydrogen and with a gaseous oxidant, usually pure oxygen or oxygen from air, and those fuel cells using direct feed organic fuels such as methanol.
In some SPE cells including many fuel cells, a cation exchange membrane is employed, and protons are transported across the membrane as the cell is operated. Such cells are often referred to as proton exchange membrane (PEM) cells. For example, in a cell employing the hydrogen/oxygen couple, hydrogen molecules (fuel) at the anode are oxidized donating electrons to the anode, while at the cathode the oxygen (oxidant) is reduced accepting electrons from the cathode. The H+ ions (protons) formed at the anode migrate through the membrane to the cathode and combine with oxygen to form water. In many fuel cells, the anode and/or cathode are provided by forming a layer of electrically conductive, catalytically active particles, usually also including a polymeric binder, on the proton exchange membrane, and the resulting structure (sometimes also including current collectors) is referred to as a membrane electrode assembly or MEA.
Membranes made from a cation exchange polymer such as perfluorinated sulfonic acid polymer have been found to be particularly useful for MEAs and electrochemical cells due to good conductivity and good chemical and thermal resistance which provide long service life before replacement. However, increased proton conductivity is desired for some applications, particularly for fuel cells that operate at high current densities.
A need thus remains in the art for compositions having properties that make them desirable for use as films from which membranes may be fabricated, which compositions also have desirable properties in other applications in the filed of electronics.